To answer the general question of how much size matters, it always matters. It doesn't determine who wins, obviously, but size has a lot to do with who wins fights many times. Especially if a fighter has the skill to go with their size advantage.

In this case I'd like to bring up Martinez-Chavez and Pacquiao-Margarito. How many lbs do you think Chavez had on Martinez? What about Margarito on Pacquiao (not sure if there was a dehydration clause for this one)? The smaller guy might not be able to KO or hurt (even tho Martinez did hurt Chavez) the bigger guy but as you can see when they are skilled they are able to inflict their damage and find their way to win.

And as far as height goes, Lara was able to school a MUCH taller Paul Williams. While Martinez gave him a tough fight in their first encounter then was able to KO him.

Not very good examples using fighters that are a level above their opponents. Fighters with a similar skill level the bigger has an advantage.

Those guys were a level above their opponents, fighters with a similar level of ability size makes a big difference.

Agreed.

We all love to see David slay Goliath, the underdog beat the favorite. It appeals to most people. It sells. But at the end of the day, the old saying, "All things being equal, a good big man will always beat a good little man," usually applies. You'd go broke always betting the other way.

Lara is more skilled and williams didn't have a size advantage against sergio, height and reach yes but not weight.

Lara may be more skilled but I don't think he was LEVELS above Williams in skills and he was less experienced. They fought at 154 so Im pretty sure he outweighed Lara on fight night too. You're probably right about Martinez and Williams tho. Not sure what their tale of the tape looked like, I kinda forgot.